Functions to find representative colors from a precomputed color
histogram. these functions just find the colors, they do not actually
quantize the images. This is done in rgbaimage, and rgbafimage.

7.3.17.0.0. (cqu-init-proto ppalproto)

(lsh/libimage/color-quantize.lsh)

initialize prototypes for K-means. assumes that
ppal contains the color values sorted by luminosity (as
returned by rgbaim-histo32). puts the prototypes regularly spaced along
a line between the darkest and lightest color.
ppal : Nx3 matrix of floats containing a list of RGB color
cells proto : Px3 matrix of floats,
contains the initalized prototypes on output

7.3.17.0.1. (cqu-kmeans ppalcountassignsplitprotolabelweightvariance)

(lsh/libimage/color-quantize.lsh)

performs a Kmeans algorithms on the color values contained in
ppal . INPUT: ppal : Nx3
matrix of floats containing a list of RGB color present in the picture
count : N matrix of floats, number of pixels with the
corresponding RGB color assign : N
matrix of floats containing the label of the prototype to which the
color cell is currently assigned. split
: an int: only those color cells whose initial assigned label is equal
to split will be taken into account.
proto : Px3 matrix of floats, contains initialized RGB
prototypes label : P matrix of ints,
contains labels for the prototypes OUTPUT: proto
: contains the updated prototypes on output
assign : the color cells whose assigned value was
split will be assigned the value in
label correspinding to their closest prototype.
weight : P matrix of float, contains the number of pixels
assigned to each prototype variance :
P matrix of float, contains the variance associated with the prototypes